Radio receiving system



Feb. 14, 1933. J. E. GARDNER RADIO RECEIVING SYSTEM Filed Aug. 23, 19261 a w H I I II. l I I I l I M 5 2 Q 6 m m a 1 9 R Z 5 llllllll 1| M 7 I5 l 6 a A, H H 0 A\ M INVENTOR %L Patented Feb. 14, 1933 UNITED, STATESPATENT, OFFICE.

Join: a. cmnnn, or CHIGAGO,ILLINOIS ,ASS1GNOR 'ro GBIGSBY-GBUNOW comm,

or cmcaco, ILLmoIs, A coaronawrou or ILLINOIS namo RECEIVING srs'rmApplication filed August 28, 1926. Serial No. 130,807.

My invention relates ingeneral to talking machines, andmore particularlyto such machines as employ a radio receiving set in will functionwithout any interference from the so-called static. f A further objectis to provide an improved magnetic rectifier that will operate toefliciently change alternating current as supplied from commercialsource to direct current, suitable for use in the talking machine. Thereare other objects of the invention which together with the foregoingwill be described in the detailed specification that is to follow, takenin conjunction with accompanying drawing forming a part hereof.

In practicing my invention, I provide a talking machine of a well knowntype. I also provide various relays for performing the automatic tuningfunction and certain other features. These switching devices have beendescribed more in detail in my co-pending application, Serial Number123,528, filed July 19th, 1926, and in my co-pending ap; 'plication,Serial Number 129,717, filed Aug- 11st 17th,1926.

In the drawing I have shown by means of the usual conventional diagrams,suflicient of the apparatus and circuits to enable my invenoton to bereadily explained and understo Referring to the drawing, the talkingmachine comprises the usual tone arm 5, mag-' netic pick-up 6, electricmotor 7, turn table 8, and record 9. Other portions of the talkinmachine comprise a power unit 10, 'amphfiers 11 and 12, loud speaker 13,milliammeter voice current relay 1&1, controlling reis to provideimproved lays l5 and 16, radio receiving set 17, connecting anddisconnecting relays 18 and 19, and controlling relays 20 and 21. All ofthis apparatus, aswell as the operation thereof, with the exception ofthe power unit 10, and the radio receiving set 17 has been described indetail in my co-pending application,

Serial Number 129,717, filed August 17th,

1926, and this description need not be repeated here. i

The power unit 10 comprises a ballast tube '22, that is merely a currentlimit reactance and transformer 23, and a resistance 24, that acts as apotentiometer. The rectifying de- 'vice proper comprises a relay 25 ofthe type ordinarily employed in the harmonlc con- Verters in theautomatic telephone art. This relay is provided with a polarizedarmature 26, having a pendulum 27 attached thereto. I This pendulum isadjusted so that the arma- 7C ture is resonant to a frequency of cycles.The armature actuates springs 28 and 29 in one position, and 30 and 31in another position.

A filter circuit 32 is associated with this rectifier so that a directcurrent having a substantial constant voltage and wave shape isobtained. This filter may be of any well known construction.

The radio receiving set is of the superheterodyne type,.and it comprisesa loop antenna 34, tuning condensers 35 and 36, oscillator triode 37,first detector triode 38, intermediate amplifiers 39 and 40, and seconddetector 41. The condenser 35 is adapted to control the tuning of theinput circuit of the first detector 38, while the condenser 36 isadapted to conated by the oscillator 37.

It is well known that there is a definite relation between the frequencyof the'incoming signal and the frequency of the oscillator for the bestresults in su erheterodyne amplifiers. It has been found t at anintermediate frequency of40,000 cycles gives very desirable results inamplification. Various types of" one dial control superheterodyne radiosets have been placed on the market. By means of these both thecondenser that controls the frequency of the oscillator are controlledby one dial; the condensers being geared so that when any station istuned in the intermediate frequency will be say 40,000 cycles.

It has also been found that for the reception of some incomingfrequency, a greater efliciency of amplification may be secured by usinganother intermediate frequency. This relation of the two condensers iscontrolled by their gearing, so that the proper frequency of oscillationis generated to bring about the formation of the proper intermediatefrequency. Condensers and 36 of the radio receiving set 13 are gearedtogether so as to prbduce these results.

These condensers are adapted to be operated by a stepping magnet 42through a pawl and ratchet device 43. The condensers are also adapted tobe operated by a motor 44 through a reducing gearing 45. The reducinggearing 45 is so constructed that when the motorris operated, thecondensers are actuated very slowly. The stepping magnet 42 is adaptedto operate by means of the calling device 46. This calling device may beof any well known type employed in the automatic telephone art, thoughit is so modified to close the circuit instead of open it, a largenumber of times. The number of impulses that are sent out by the callingdevice is controlled by the degree of nicety required in adjusting thecondensers 35 and 36.

It has been found that if the calling device is adapted to send outimpulses for one revolution, and the ratchet and pawl arrangement 43 ofthe stepping magnet 42 arearranged so as to advance the condensers 35and 36 to degrees, that this will be satisfactory for most purposes.

The call letters of any particular station may be placed in the fingerholes in the dial, or any such position where the operator may actuatethe calling device for the required number of impulses, and release key47 is associated with the calling device and controls the restoration ofthe condensers 35 and 36 to a normal predetermined osition. Thisoperation is brought about y a cam switch 48, which actuates a air ofsprings when this normal predetermined osition is reached.

The output circuit 0 the last intermediate amplifier 40 is associatedwith the milliammeter relay 49 through a band filter 50. The band filtermay be of any well lmown type, and is adjusted so as to be resonant onlyto the particular intermediate frequen that is used for intermediateamplification o any'station that happens to. be tu'nedin. As thisfrequency may vary, as explained hereinbefore, means. are provided foradjusting the frequency to which the band filter is responsive throughthe shaft 51, which is operated by means of-the motor 44.

In this manner when a station is tuned in, 'the band filter 50 isadjusted so that it is only responsive to the particular intermedi- Apush button key 53 is provided for connecting energy to the talkingmachine. A single throw key 54 is provided for controlling theinitiating of the automatic tuning of the device, as will be explained.

Having briefly described the apparatus shown in the drawing, I will nowexplain its detailed operation. If the operator desires to play thephonograph alone, he will operate the push button 53 Tand the key 54intoposition A The operation of the key 53 completes a circuit for thealternating relay 18. Alternatin relay 18 operates to attract itsarmature, t ereby connecting the alternating current energy from thesource 55, through the primary of the transformer 23. The armatures ofthe relay 28 are latched in operative position by the armature of the rlay 19 by the flow of alternating current through the primary of thetransformer 23, and alternating current is induced into the secondary ofa voltage which is determined by the relative number of turns of onewinding to the other. This voltage is determined by the proper voltagesnecessar to operate the talking machine. When alternating current isinduced into the secondary of the transformer 23, the harmonic relay 25is operated.

To explain the operation of the rectifier, the operation will bedescribed when there is a positive wave of alternating current inducedinto the secondary. Inasmuch as the armature 26 of the relay 25 ispolarized, this armature willswing in such direction as to' force thesprings 28 and29 into. engagement with their working contacts. A circuitmay now be traced that extends from the lower end of the transformer 23spring 29 and its .working contact filter 32 to one side of thepotentiometer, while the other portion of the circuit extends from theupper sidefof the transformer 23 spring 28 and its working contactfilter 32, to the other side of the potentiometer 24. When there isa'negative wave in the secondary circuit, the relay 25' operates itsarmature 26, so that the springs 285m 29 are opened, and the springs 30and 31., are forced into engagement with their working contacts.

It will be seen that the connections of the secondary of the transformer23 with respect to the potentiometer 24. are reversed under theseconditions. This reversal occurs with each half wave of the alternatingcurrent, so that the current always flows in the same direction to thetwo terminals of the potentiometer. The relay 25 thus functions as arectifier. ,Inasmuch as-thearmature 26 of its operation will besynchronous wit the,

reversal in polarity in the alternating current, so that fullwaverectification is secured with very high efiiciency.

The filter 32 functions to smooth out the wave, so as to form acontinuous current out of an impulsing direct current that is obtainedfrom the rectifier. The potentiometer 24 is employed so that variousvoltages ma be obtained, the mid-point of the potent1- ometer being zeropotential.

It will be understood that any other form of rectification may beemployed in place of the one described. As soon as the rectifier beginsto function, the lamp 56 is energized to apprise the operator of theconnection of electric energy to the talking machine. It

will then release the key 53, thereby opening the circuit of the relay18. This result is without function, because the armatures of this relayare latched in their operated position when record 9 is placed upon theturntable 8, and the tone arm moves so that the needle in the magneticpick-up 6 engages 'the first groove in the record, and re-set magnet 57is operated to initiate the rotation of the turn-table.

Loud speaker 13 is operated to reproduce the sounds recorded on therecord. The milliammeter relay 14 is operated to open its contacts solong as there are sound currents present in the output circuit of theamplifier 12. Shortly before the'end of the record, the tone arm causesthe operation of a set of contacts 58- so that the slow acting relay 16is energized. When the record is ended, sound waves are no longerpresent in the output circuit of the amplifier 12, and the milliammeterrelay 14 is de-energized to permit its contacts to energize, therebyclosing the circuit for the relay 15. The relay 15 is energized toopenthe circuit of the slow acting relay 16, which is de-energized aftera short interval of time, to complete a circuit for the release magnet60. The release magnet 60 operates to stop the record, anddisconnectenergy from. the motor 7.

Another result of the operation of the release magnet is that a circuitis closed for the slow to operate relay 20. If no other record isplayed, slow to operate relay 20 is energized for a considerable periodof time to complete a circuit for the relay 19, which operates todisconnect electric energy from the talking machine.

If thevoperator plays another record, the operations proceed in themanner described.

All the above operations have been described more in detailin myco-pending application, Serial Number 129,717 filed August 17th, 1926,to which reference is made if a w more complete explanation is desired.

placed in the motor ometer, springs 58, springs 61, working contact ofspring 62 and said spring relay 21, to the mid-polnt on thepotentiometer. The relay 21 is energized to prepare a circuit for 44 atarmature 63, and to complete circuits for energization of the filamentsof the triodes 37 to 41 inclusive, at armatures 64 and 65. 7

Another result of the operation of the relay 21 is that at armature 67 acircuit is completed that extends from a connection uponthepotentiometer through the springs of the milliammete front contacrelay 66 to the midpoint of the potentiometer. The relay 66 is energizedover thiscircuit and operates to complete a circuit for the slow to oerate relay 20 at armature 68 and to comp etc a circuit at armature 69for the motor 44 over a path that extends from one connection on thepotentiometer, motor 44, armature 69 and its front contact,front'contact and armature 63 to the midpoint of the potentiometer. Themotor 44 is operated over this circuit to movethe rotors of thecondensers 35 and 36 slowly. The operation of-the motor 44 also causesthe relay 49, armature 67 and its movement of the shaft 51 controllingthe tun:

ing of the band filter 50.

By the energization of the filaments of the triodes 37 to 41 inclusivethe radio receiving set 17 is energized so that it will respond to anincoming signal. .FBy the energization of the filament of the triode 37this triode generates an oscillating current the frequency of which iscontrolledby the condenser 36. When the condenser 35 is adjusted so thatthe input circuit of the detector 38 is resonant to the frequency of thebroadcasting station the rotor of the condenser 36 will be in suchposition so that the proper local oscillation is 'set up by theoscillator 37 so that the hetero-,

dyne beat waveis formed having the desired frequency for maximumamplification.

With the condensers 35 and 36 in this posiapplied to the band filter,and as this band filter is tuned for this frequency current flows in thearmature of the milliammeter ,relay 49. The relay 49 is so adjusted thatan amount of current suflicient to operate it rerquires that the:station be tuned in properly. If the operator desires to listen to theradioi;

after the. record is played, the key 54 is frelay 66 is opened anthelatter relay is deenergized to open the circuit of the motor 44 atarmature 69 and to open the circuit of the relay 20 at armature 68fThe'motor 44 immediately ceases to operate and the condensers and 36remain in the position in which they are set with the station tuned in.

The amplifiers 11 and 12 operate to amplify the sound waves from thebroadcasting station and apply them to the loud speaker 13. The relays14, 15 and 16 are operated at this time but their operation is withoutparticular function. When the station signs oif the relay 49 isimmediately deenergized as the carrier Wave from the broadcastingstation is shut down and there is no intermediate frequency present inthe radio receiving set. The deenergization of the relay 49 completes acircuit for the relay 36. The relay 36 operates to again close thetuning circuits. Another station is automatically tuned in in the samemanner as described. If no other station happens to be broadcasting atthis time the slow to operate relay 20 will be finally energized tocomplete a circuit for the relay l9 and operates to disconnect theelectrical energy from the. talking machine.

A slight modification of the automatic tunmg equipment associated withthe radio set gives a somewhat more preferable operation. In thisinstance the radio receiving set is adapted to, operate with only oneintermediate frequencthis frequency being the frequency at w ich optimumintermediate am:

plification is secured. The hand filter 50 is then tuned so as torespond only to this frequency. T he tuning of the band filter is notunder these conditions controlled 'by the motor 44. With the equipmentarranged in this manner, unless a broadcasting station is exactly tunedin by the automatic tuning equipment, the intermediate frequency willnot be exactly that to which the band filter 50 is responsive. Until theintermediate frequency corresponds to this frequency which the bandfilter 50 is responsive the relay 49 will not be operated. 'Whenthestation is properly tuned in the relay49 will respond and the operationswill occur substantially as described.

It sometimes happens that the operator desires to tune in a particularstation. In order that he may do this a calling device 46 is providedtogether with a key 47. This calling device may be located on thetalking machine or at a point remote therefrom. As mentioned before, thecalling device is provided so that it may send a hundred impulses. Thevarious stations are so designated on the calling device that it may beproperly operated to send out a number of impulses which will set thecondensers 35 and 36 in approximate position to tune in the requiredstation. The release key 47 must be operated before the calling device46 is operated. By the operation of the release key a circuit iscompleted for operating the magnet 42 as a buzzer until the condensers35 and 36 are brought to a predetermined normal position. When thecondensers are in this position a certain fixed number of impulses fromthe calling device 46 will place the condensers in the proper positionfor tuning in the particular station. When the calling device isoperated in accordance with the code the stepping magnet 42 is energizedsuccessively a plurality of times until the condensers are brought intothe desired position. Now, when the automatic tuning device of the radioreceiving set is operated by the energization of the relay 66 as beforedescribed, the first station that will be tuned in will be the one whichis approximately selected by the setting ofthe condensers. The tuning inof this station proceeds in exactly the same manner as has beendescribed.

The operator sometimes desires to disconnect energy from the talkingmachine when a particular radio station signs off. In order toaccomplish this result a key 70 is provided. The key 7 0 is thrown aftera particular station is tuned in. Now, when the selected station ceasesto broadcast the carrier Wave is no longer sent out and the relay 49 isdeenergized to complete'a circuit for the relay 66. The relay 66 isoperated to initiate the automatic tuning and to complete a circuit atarmature 71 for the relay 19. The relay 19 is energized to disconnectelectrical energy from the talking machine in the manner described.During any of the radio receiving operations the operator may play thephonograph by moving the tone arm into position to play another record.The movement of the tone arm causes he energization of the reset magnet57 which opens the circuit of the relay 21. The relay 21 is deenergizedto disconnect the radio receiving set.

It will be seen that the normal condition of the talking machine is suchthat the radio set may be immediately operated as soon as the pushbutton 53 is operated. This is true because the tone arm will be in itsinnermost position and the reset magnet 57 will not be energized norwill its armature be latched in an operative'position. Therefore, assoon" as energy is connected to the talking machine the relay 21 will beenergized to connect the radio receiving set and the operation willproceed as before described.

Attention is directed to the fact that when the key 70 is operated aftera radio broadcasting station is tuned in and the radio station signsoff. the electrical energy will be immediatelydisconnected from theradio receiving set. Inasmuch as the relay 49is operated at the laststage of intermediate amplification a considerable amount of currentwill flow through its armature and it will efliciently operate toperform the functions described. The relay 49 is energized all the whilea broadcasting station is tuned in until the stations carrier waveceases. The relay is not afiectedby any change in the modulation fromthe station nor is it dependent upon sound currents.

but desire to protect by'Letters Patent such changes, deviations andmodifications as come within the scope of the appended claims.

- lclaim:

1'. A radio receiving set comprising in combination, means for receivingradio frequency oscillations, means for producing local os- .cillationsand combining the local oscillations with the received oscillations tocreate oscillations of a difierent frequency, means for tuning thereceivin set ,to render it responsive to received ra 'io frequencyoscillations havin a definite frequency,'and means controlled by theoscillations of said received definite frequency" to control said tuningmeans. a

2. A radio receiving set comprising-in combination, means for receivingradio frequency oscillations, means for producing local oscillations andcombining the local oscillations with the received oscillation to createoscillations of a different frequency, means for automatically tuningthe receiving. set' to render it res onsive to received radio fr'equency oscil ation having a definite fre quency, and means contro ed bythe oscillations of said diiferentfrequency to control said tunin means.7

3. A ra 10 receiving set comprising inc'ombination, means for receivingradio fre-', quency oscillations, means for producinglocal oscillationsand combining the local'os cillations' with the received oscillations tocreate oscillations of a different frequency, means for amplifying saiddifferent frequency oscillations, means for tuning said receiving set torender it responsive to received radio requency oscillations, having adefinite frequency, and means controlled by. said amplified oscillationsfor operating said tuning means.

4. A radio receiving set comprising in combination, means for receivingradio frequency oscillations, means for producing local oscillations andcombining the local oscillations with the received oscillations tocreate oscillations of a difierent frequency, means for tuning saidreceiving set to render it responsive to received radio frequencyoscillations having a definite frequency, and means including a relaydevice responsive to said different frequency oscillations forcontrolling said tuning means.

5. A radio receiving station comprising in combination, a circuit forreceiving radio freuency oscillations, tuning means for altering t eperiodicity of said circuit, a receiving device for convertingelectrical oscillations to audible waves means for producing local radiofrequency oscillations and combming them with the received radiooscillations to create intermediate frequency oscillations,

means for causing said intermediate frequency oscillations to operatesaid receiving device and means for causing said intermediate frequencyoscillations to control said means.

tuning r 6. radio receiving station comprisin in combination, a circuitfor receiving radio equency oscillations, tuning means for altering theperiodicity of said circuit, a receiving device for convertingelectrical oscillations to audible waves, means for producing localradio frequency oscillations and combining them with the received radiooscillations to create intermediate frequency oscillations to operatesaid receiving device and means including a relay responsive to saidintermediate radio frequency oscillations for controlling said tuningmeans. 7

7. A radio receiving station comprising in combination, a circuit forreceiving radio frequency oscillations, tuning means for altering theeriodicity of said circuit, a receiving device for converting electricaloscillations to audible waves, means for producing local radio frequencyoscillations and combining them with the received radio oscillations tocreate intermediate frequency oscillations to operate said receivingdevice, a motor for operating said tuning means and means for causingsaid intermediate frequenqg oscillations to control said motor.

' 8. radio receiving station comprising in combination, a circuit forreceiving radio frequency oscillations, tuning means for altering theperiodicity of said circuit, a receiving device for convertingelectrical oscillations to audible waves, means for producing localradio frequency oscillations and combining them with the received radiooscillations to create intermediate fre uency oscillations to operatesaid receiving evice, a motor for operating said tuningmeans, and arelay responsive to said intermediate frequency oscillations adapted tocontrol said motor.

9. A radio receiving station comprising in combination, a. circuit forreceiving radio frequency oscillations, tuning means for altering theperiodicity of said circuit, a receiving device for convertingelectrical oscillations to audible waves, means for producing localradio frequency oscillations and combining them with the received radiooscillations to create intermediate frequency oscilv means including awave band filter for applying said intermediate frequency oscillationsto said relay.

10. A radio receiving station comprising in 5 combination a circuitresponsive to radio frequenc oscillations, means for producing local raio frequency oscillations and combining them with received radiofrequency oscillations to produce a heterodyne oscilla- 10 tion, tuningmeans for altering the periodicity of the circuit responsive to radiofrequency oscillation and the frequency of the local generated radiofrequency oscillation arranged so that when the receiving circuit 15 isresponsive to a certain periodicity a predetermined heterodyne frequencywill be produced and means responsive to said predetermined frequencyfor controlling said tuning means. Y y 39 11. A radio receiving stationcomprising in combination a circuit responsive to radio frequencyoscillations, means for producing local radio frequency oscillations andcombining them with received radio frequency oscillations to produceaheterodyne oscillation, tuning means for altering the periodicity of thecircuit responsive to radio frequency oscillation arranged so that whenthe receiving circuit "is responsive to a certain periodicity apredetermined heterodyne fre-' quency will be produced and meansincluding a elay device responsive to a predetermind .eterodynefrequency to control said tuning means. 35 12. Aradio receiving stationcomprising in combination a circuit responsive to radio frequencyoscillations, means for producing local radio frequency oscillations andcombining them with received radio frequency oscillations to produce aheterodyne oscillation, tuning means for altering the periodicity of thecircuit responsive to radio frequency oscillation arranged so that whenthe receiving circuit is responsive to a certain periodicity apredetermmed heterodyne frequency will be produced, means responsive toa predetermined heterodyne frequency for controlling said tuning meansand auxiliary means for controlling said tuning means to limit theoperation of the means responsive to heterodyne frequency to a definitepredetermined periodicity of said receiving circuit.

JOHN E. GARDNER.

